I went with KAC when I dealt with that problem a couple years ago, 20" SR25. It's almost a completely proprietary rifle and it's also damn nice. It's got everything you'd want, it's ambi but it's made that way, all built in, no shit hanging off of it or an afterthought in engineering. It's made that way, bolt and mag release buttons on both sides, same as safety. Cut rifle barrels. The one piece keymod (or mlok) tube makes the upper practically monolithic and long enough for any scope/NV combo. The suppressor made for it is one of the best "all around" I've ever seen or used. It's expensive, but you get what you pay for. If you qualify for a military account or any discounts (just ask) the prices can be quite a bit lower. For MSRP price, I got the rifle, plus the cleaning kit with the extra bolt parts and ten extra mags. Not bad. Guaranteed less than 1MOA, comes with target. Nice, spiral bound manual. It's really nice and I like it. If you want a more "combat" version, they have one in 16", still cut rifled, but also chrome lined. It weighs about 2lbs less than the heavy barreled 20" and costs a bit less. There's a heavier non-chrome lined 16" too.
If you got the money and are into looks, you can shell out the $10k or so for one of the military M110 variants that comes with all the goodies, a drag bag and a Pelican hard case. Also comes with the Leupold scope. Suppressor and NV cost extra. Or you can get the one I just described for with all the stuff for far less and it's basically the same rifle but newer.
It's one of my favorite rifles, was the day I got it. I'd wanted one forever. It's damn nice and you don't need to change shit when you get it. If you like Magpul grips over stock AR grips, you may wanna change that, but that's it. If you like AR grips, you're good to go. Slap a bipod and a scope on it and it's ready to go. Already has the $400+ flip sights pre installed and comes with grip covers and a couple of rail sections. I think it came with a sling socket too. And a sticker, all the good mfg.'s always include stickers, and I like that.
Yet another one to consider is the HK, it's the new M110A1 for the army, 16" hammer forged I believe with a gas piston. If I wanted gas piston in one of these, I'd probably consider HK. Although you can't get it exactly like the G28 OR the one they issue to our army. Bullshit.
The LMT rifle is nice, but I didn't think it was worth the price compared to others. The MWS? The one Britain chose for SDM's?
The Larue OBR is nice but the waiting list put me off on that one at the time. Same with GAP. And GAP wouldn't customize any parts, even if I sent them to be installed. FN said a year for their rifle, but I fell for that before, not this time, and sure enough their precision rifle was/still is delayed. If it ever gets mass produced. I tried some other SR knockoffs and none of 'em really held up like the real thing.
Glad I jumped on the SR25, only wish I'd done it sooner. And you can get it in 6.5Creedmore now! Get the 16" chrome lined rifle, and the 6.5 upper separately and you'll have two rifles basically. Damn nice ones.